Radium-223 for mCRPC, a real-world experience study from 7 Galician medical centers.

Abstract

96 Background: Radium-223 represents an option for symptomatic metastatic castration-resistant prostate cancer (mCRPC) after demonstrated an overall survival improvement in the ALSYMPCA trial. Radium-223 real-life experiences are scarce, particularly after the results of the ERA-223 trial. To describe Radium-223 outcomes in real life practice, and specifically those related with bone health, sequence of treatment, and prognostic factors. Methods: Multicenter retrospective study of a cohort of 143 patients with mCRPC treated with Radium-223 in either the second line or third line of therapy or beyond in the context of routine clinical practice between 11 March 2013 and 26 July 2022, in seven Galician hospitals. Survival estimates were calculated by the Kaplan-Meier method, and groups were compared with the log-rank test. The Cox proportional hazards regression model was used to evaluate factors independently associated with OS. Between March 11, 2013, and July 26, 2022, 143 patients were enrolled from 5 Galician hospitals. With a median follow-up of 9.68 months. All patients signed an informed consent form agreeing to participate in this observational study, that was approved by the Galician Ethics Committee, registration code 2018/282. Results: Baseline patient and disease characteristics are summarized. Median follow-up was 9.68 months. Median overall survival (OS) was 12 months (95% CI 9.7 – 16.0). Best OS outcomes were achieved in second and third line, 18 months (95% CI 12.0 – 26.0) and 9.4 months (95% CI 8.0 – 12.0) months, respectively. Among those baseline clinic-analytical factors analyzed, only alkaline phosphatase level >354 UI/L was correlated with a worse OS (HR 2.56 (95% CI 1.39 – 4.72; p=0.003) and the number of cycles of Radium-223 received (HR 0.63 (95% CI 0.54 – 0.73; p<0.001) were prognostic factors for Radium-223. Importantly, ninety-nine of patients (80%) were treated with bone-targeted therapy for bone metastases with no OS differences (p=0.66). Conclusions: In our study, Radium-223 efficacy was consistent with previously reported. Best efficacy was achieved in the second or third line of therapy, independently of docetaxel use. Patients with high baseline alkaline phosphatase had worse OS. Few patients presented skeletal-related events, which could be explained by an adequate use of bone-targeted therapy (zoledronic acid or denosumab). [Table: see text]